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Does the Pill Lower Ovarian Cancer Risk?

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Updated March 03, 2011

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Question: Does the Pill Lower Ovarian Cancer Risk?
Ovarian cancer is cancer that starts in the ovaries. It is the fifth most common cancer among women, and it causes more deaths than any other type of female reproductive cancer. It is estimated that approximately 30,000 new cases of ovarian cancer will be diagnosed each year, with 15,000 women dying from this disease.
Answer:

More than two-thirds of U.S. women will use hormonal contraception sometime during their reproductive years, yet many women are unaware of the noncontraceptive benefits of using this type of birth control. In general, combination hormonal contraceptives consist of a progestin and a synthetic estrogen. Some hormonal contraceptives also have the extra benefit of reducing ovarian cancer risk.

Please be aware that the main reason to use hormonal contraception is for contraception (to prevent an unintended pregnancy) -- possible noncontraceptive benefits can be considered when determining which hormonal birth control method to choose.

The following is a list of specific prescription birth control methods that have been shown to be effective in lowering the risk of ovarian cancer:

  • The Pill: Research has shown that if you take the pill for 15 years or more, your ovarian cancer risk is reduced by 58%; 10-14 years of pill use lowers your risk by 44%; and 5-9 years of pill use cuts your risk by 36%. Even women who used the pill for only 1-4 years saw a benefit (reducing their ovarian cancer risk by 22%).

    It seems that this protective benefit may become weaker the longer it had been since a women used the pill; however, the protective effect was still significant even 30 or more years after pill use stopped. According to the Collaborative Group on Epidemiological Studies of Ovarian Cancer (2008), over the past 50 years, it is estimated that 200,000 cases of ovarian cancer and 100,000 deaths worldwide have been prevented by oral contraceptive use, and that if use remains at the current level, as many as 30,000 ovarian cancers could be prevented each year.


  • Low-Dose vs. Higher Dose Pills: Lower-dose oral contraceptives contain the lowest amount of estrogen (20 mcg) plus one of the eight types of progestin. Regular-dose pills contain 30–35 mcg estrogen plus progestin, and high-dose pills have around 50 mcg of estrogen plus progestin. The reduced risk of ovarian cancer in Pill users is thought to be due to the hormones suppressing ovulation. Studies indicate that there does not appear to be a different level of ovarian cancer risk reduction from different estrogen doses in the pill. The protective effect (against ovarian cancer risk) has been shown to extend to low-dose pills as well as regular and high-dose ones.

    Researchers from Duke University Medical Center suggest, however, that the progestin levels in the oral contraceptives might be as important as ovulation reduction in the prevention of ovarian cancer. After comparing birth control pills by both estrogen and progestin potency, the researchers found that oral contraceptives with higher levels of progestin were associated with greater ovarian cancer risk reduction than those with lower progestin potency (regardless of estrogen content). The study also indicated that women who took pills with higher progestin levels showed a significant reduction in risk, even when taken for a short amount of time (3-18 months). The amount of estrogen in the pill did not seem to affect ovarian cancer risk.


  • Depo Provera: The progestin-only Depo Provera injection also shows a similar protective effects on ovarian cancer risk. This is most likely due to how the progestin may suppress ovulation.

  • NuvaRing and Ortho Evra Patch: Given that both of these birth control methods contain a combination of progestin and estrogen, it is thought that they should allow the same protective benefit from ovarian cancer as combination birth control pills do. Research, however, is limited.

Sources:

Collaborative Group on Epidemiological Studies of Ovarian Cancer. "Ovarian cancer and oral contraceptives: Collaborative reanalysis of data from 45 epidemiological studies including 23,257 women with ovarian cancer and 87,303 controls." Lancet 2008;371:303–14. Accessed 2/24/11.

Ness RB, Grisso JA, Klapper J, Schlesselman JJ, Silberzweig S, Vergona R, et al. "Risk of ovarian cancer in relation to estrogen and progestin dose and use characteristics of oral contraceptives." SHARE Study Group. Steroid Hormones and Reproductions. Am J Epidemiol 2000;152:233–41. Accessed via private subscription.

Schildkraut JM, Calingaert B, Marchbanks PA, Moorman PG, Rodriguez GC. "Impact of progestin and estrogen potency in oral contraceptives on ovarian cancer risk." JNCI J Natl Cancer Inst 2001: 94(1):32-38. Accessed via private subscription.

The American College of Obstetricians and Gynecologists. "Noncontraceptive uses of hormonal contraceptives." Practice Bulletin No. 110, Jan 2010 115:206-18. Accessed via private subscription.

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